Apex domains cannot have CNAME records.
Question and response
Question
dig net4all-dns.com. NS
Answer
net4all-dns.com. 5 NS dns02.net4all-dns.com.
net4all-dns.com. 5 NS dns01.net4all-dns.com.
Authority
The response has no authority records.
Additional
dns01.net4all-dns.com. 5 A 141.101.62.86
dns02.net4all-dns.com. 5 A 141.101.62.129
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0